In the production of semiconductor wafers and other semiconductor articles and workpieces it is desirable to automate the production to varying degrees. If power is lost or if there is a malfunction in the controller or related functions, then the control system may not have information indicating whether a machine has a wafer or other semiconductor workpiece present. Accordingly, it is desirable to have means for determining whether a wafer is present within a processing station without requiring manual inspection.
Any wafer detection system must be robust to stand up to the oftentimes harsh chemicals and vapors present in processing semiconductors. Thus there is a need for improved subsystems for use in semiconductor wafer support heads which allows for reliable detection of the presence or absence of a wafer therein.